A common and well-known form of harvesting machine is a rotary combine. Rotary combines are available in various designs and models to perform the basic functions of harvesting, threshing, and cleaning of grain, and other crop materials.
A typical combine includes a crop harvesting apparatus which reaps planted grain stalks and then feeds the grain stalks to a separating or threshing apparatus. The grain stalks or other crop harvested in the field is rearwardly moved from the crop harvesting apparatus and introduced to a threshing assembly by a feeder mechanism.
In an axial-flow combine, the threshing assembly includes a generally tubular rotor casing mounted on the frame of a combine and a driven rotor disposed within the casing in coaxial relationship therewith. The rotor is supported at opposite ends by front and rear bearing assemblies. The rotor and casing have cooperating threshing instrumentalities arranged thereon for separating grain from material other than grain. In such a combine, which has been available for a number of years, the grain is threshed several times repeatedly, but gently, as it spirals around the rotor and passes through openings in the rotor casing.
The ability to transfer crop material from the feeder mechanism to the rotor assembly is a key factor in efficient and effective combine operation. Different types of embodiments of infeed assemblies have been known to be used to transfer crop material from the feeder mechanism to the rotor assembly. U.S. Pat. No. 4,250,896 to R. Wagstaff, et al. discloses an infeed assembly in the form of an auger. Alternatively, U.S. Pat. No. 4,148,328 to R. E. McMillen discloses a bladed impeller driven by the rotor. With either embodiment, a transition housing or section is typically arranged at the forward end of the rotor casing and surrounds the infeed assembly. An inner surface of the transition housing cooperates with the infeed assembly in inducing axially rearward motion to the crop material.
An auger-type infeed assembly offers aggressive advancement of material from one location to another. An auger type infeed mechanism, however, also has drawbacks. For example, an auger-type infeed mechanism tends to plug easily thereby effecting combine efficiency. Moreover, the auger-type infeed mechanism tends to rearwardly move crop material close to the axial center of the rotor and therefore neither combs the crop material into a thin annular mat nor meters the crop material to the rotor assembly.
An impeller blade type infeed assembly offers enhanced radial outward movement of the crop material toward the transition housing of the rotor casing. The radial outward movement of the crop material tends to comb the material into a thin annular mat which is introduced in a metered fashion into the rotor assembly The feeding action of an impeller blade type infeed assembly, however, is less aggressive than that afforded by auger-type infeed assemblies.
When axial-flow combines are used in certain long-stemmed leguminous or grassy crops, such as windowed perennial or annual rye grass, clover and bent grass, there is a potential for such grassy crops to extend partially into the infeed assembly while the remainder of the crop material extends to the feeder mechanism. That portion of the elongated grassy crop material extending into the infeed assembly typically passes over the blade on the auger or of the impeller and tends to hair pin about an outer blade edge and move toward the axis of rotation of the rotor assembly. Some of such crop material tends to wrap about the front rotor assembly bearing.
As will be appreciated, if the crop material becomes tightly wrapped about the rotor bearing assembly, it can impair the operational characteristics of the combine. Crop material wrapping about the rotor bearing assembly has been known to eventually damage the operational components of the rotor by breaking the seals on the bearing assembly and, ultimately, stall the engine. To clean and clear this problem, of course, requires valuable time which is at a premium in a crop harvesting operation. Repair or replacement of a bearing assembly consumes still more valuable harvesting time.
Crop material is fed endwise into the forward end of the infeed assembly in an undershot fashion. The whirling action of the infeed assembly blades has the a tendency to block crop material from entering the infeed assembly. The backlash effect of residual crop material also tends to inhibit crop material from entering the infeed assembly. The tendency of the infeed assembly to reject incoming crop material reduces the full potential of the combine by inhibiting the rotor assembly from operating at its full capacity.
Thus, there is a need and a desire for an infeed assembly which offers an aggressive crop material feeding action commensurate with capacity of the rotor assembly and which tends to move crop material radially outward from the front rotor bearing to facilitate its axially rearward movement through the rotor assembly.